From the 1930s to the 1960s, the income of the less affluent Americans grew more quickly than that of their wealthier neighbors, and the richest 1 percent saw its share of the national income shrink to 8.9 percent in the mid-1970s, from 23.9 percent in 1928. That share is now back up to more than 20 percent, its level before the Depression.

Inequality has traditionally been acceptable to Americans if accompanied by mobility. But most recent studies of economic mobility indicate that it is getting even harder for people to jump from one economic class to another in the United States, harder to join the elite. While Americans are used to considering equal opportunity and equality of condition as separate issues, they may need to reconsider. In an era in which money translates into political power, there is a growing feeling, on both left and right, that special interests have their way in Washington. There is growing anger, from the Tea Party to Occupy Wall Street, that the current system is stacked against ordinary citizens. Suddenly, as in the 1930s, the issue of economic equality is back in play.

It was all predicted, but the unanimous decision by Senate Republicans on Tuesday to filibuster and thus kill President Obama’s jobs bill was still a breathtaking act of economic vandalism. There are 14 million people out of work, wages are falling, poverty is rising, and a second recession may be blowing in, but not a single Republican would even allow debate on a sound plan to cut middle-class taxes and increase public-works spending.

As bad as the overall economic situation may be, the creative class has in fact gotten off comparatively lightly. The creative class added nearly three million jobs between 2001 through 2010, growing jobs at a seven percent clip. And the sub-group of the creative class that spans arts and media grew at nearly double that rate (13.8 percent) over the same period. Average creative class wages increased by more than a third (34.5 percent), from $52,707 to $70,890, over this decade—more than any other major occupational group—and wages for arts and media creatives rose by 31.5 percent. To Timberg’s point, that these gains were not shared equally across the creative class: there were indeed winners and losers. The biggest job losses occurred among “news analysts, reporters, and correspondents” (a category that lost 15,130 jobs, a substantial 22.9 percent decline), musicians and singers (8,830 jobs lost, down 16.9 percent), photographers (10,810 jobs lost, down 16.5 percent) and editors (5,050 jobs lost, down 4.9 percent). But other segments of the creative class experienced substantial job growth. Jobs for producers and directors went up by nearly 80 percent (36,770 new jobs); art director jobs grew by 45 percent; nearly 60,000 new jobs opened up for graphic designers (up 45 percent); and audio and video equipment technician jobs increased by roughly 40 percent. But these changes pale in comparison to the decimation of the working class – spanning manufacturing, construction and transportation – which lost a staggering 6.2 million jobs.

So how important is equality? According to the study, making an economy’s income distribution 10 percent more equitable prolongs its typical growth spell by 50 percent. In one case study, Berg looked at Latin America, which is historically much more economically stratified than emerging Asia and also has shorter periods of growth. He found that closing half of the inequality gap between Latin America and Asia would more than double the expected length of Latin America’s growth spells. Increasing income inequality has the opposite effect: “We find that more inequality lowers growth,” Berg says.

Berg and Ostry aren’t the first economists to suggest that income inequality can torpedo the economy. Marriner Eccles, the Depression-era chairman of the Federal Reserve (and an architect of the New Deal), blamed the Great Crash on the nation’s wealth gap. “A giant suction pump had by 1929-1930 drawn into a few hands an increasing portion of currently produced wealth,” Eccles recalled in his memoirs. “In consequence, as in a poker game where the chips were concentrated in fewer and fewer hands, the other fellows could stay in the game only by borrowing. When the credit ran out, the game stopped.”

Many economists believe a similar process has unfolded over the past decade. Median wages grew too little over the past 30 years to drive the kind of spending necessary to sustain the consumer economy. Instead, increasingly exotic forms of credit filled the gap, as the wealthy offered the middle class alluring credit card deals and variable-interest subprime loans. This allowed rich investors to keep making money and everyone else to feel like they were keeping up—until the whole system imploded.